The emulsifying properties of protein extracts from perennial ryegrass (Lolium perenne L.) depend on the extraction method

Protein extracts from green leaves, consisting of mainly RuBisCO, have potential applications for human consumption. However, their properties are highly influenced by the extraction process applied. This work assessed the impact of the extraction method on the solubility profile and emulsifying properties of two protein concentrates from perennial ryegrass, obtained using two different approaches. These two methods differed in the application (or absence) of a heating step (50 °C for 30 min) to improve the removal of chloroplast material. The functionality of both protein concentrates was highly influenced by the isoelectric point of the proteins. The extract containing less residual chloroplast material showed greater solubility, up to 40 % more, and superior emulsifying capacity and stability, at non-acidic pH, similar to WPI. At pH above 6, the protein extract which contained residual chloroplast material was significantly less soluble, which limited its performance as emulsifier. Therefore, the extraction process critically impacted the final product's functionality. This work demonstrated that effectively removing chloroplast material is essential to achieve targeted techno-functional properties of an ingredient and the food product in which it is used.